Posted by Jim Cochran and Kristy Tinto
A team of scientists have returned to Punta Arenas Chile to operate the IceBridge mission, headed up by NASA. IceBridge will collect data on the polar ice cover for a 6 year period while NASA gears up to replace the ICESat satellite that retired from service earlier in 2010. Lamont-Doherty Earth Observatory has a team of scientists working on this project.
Our return to the Southern hemisphere for IceBridge Antarctica 2010 began without a hitch. Equipment was readied, test flights were flown, and science teams were assembled. IceBridge was scheduled to fly a series of long 10-12 hour flights from Punta Arenas, Chile over Drake’s Passage, and across the Southern Ocean. Once along Antarctic’s perimeter we would measure the Sea Ice (both extent and thickness), and a series of active ice streams, glaciers and ice shelves in West Antarctica. Many of the flights are repeat lines from 2009 in order to capture ice sheet changes, but some of the glacier flights have been extended to reach back further into the origin of the flowing ice, in order to get a better sense of the dynamics that are occurring at the heads of these accelerating ice streams. A few new lines have also been added.
As I noted all was going without a hitch, until we arrived in Chile. Our flights require large expanses of clear skies over the ocean and the peninsula for us to be able to run our instruments and collect the data we need. Antarctica’s weather, however, is extremely unpredictable at this time of year with foul weather systems setting up as cold air pours off the continent and collides with the warmer ocean surfaces. We have been watching day after day of rotten weather and cloudy conditions sideline our flights. An added complication is the length of the flight to get to location and the variability of the weather. Each time a flight is cancelled considerable planning goes into determining if a replacement flight can be flown over an alternate area that requires differing conditions. One of the priorities early in the season is to fly the sea ice flights.
Sea ice flights are collected early in the season in order to get a consistent measure of the ice extent before the ocean warms and the ice thins. Despite cloud interference causing some data gaps, there is a sea ice flight we managed to complete and consider an overwhelming success! This flight involved connecting with and under-flying the active European satellite called CryoSat-2, which was orbiting over the same section of the Weddell Sea as we were flying. With some careful calculations and a few last minute flight adjustments to deal with a strong tail wind, the Cryo-Sat-2 satellite cruised 450 miles above the aircraft as we passed underneath (see image). By collecting data in the same place at the same time with both the aircraft and the satellite we can improve the calibration of the two systems and refine any issues that might exist between the two data sets.
Jim Cochran is a geophysicts at Columbia University’s Lamont-Doherty Earth Observatory in the Marine Geology and Geophysics division. Jim has worked extensively on processes under the Earth oceans including several projects in the Arctic Ocean including the Gakkel Ridge, a mid-ocean ridge spreading center in the central Arctic, and the adjacent Amerasian Basin. Jim brings extensive gravity expertise to this project.
Kirsty Tinto hails from Northern Ireland and spent the last 12 years studying geosciences in the UK and New Zealand which has had her doing all sorts of fieldwork on land, sea and ice. She has done geophysics work including gravity surveys on the Southern McMurdo Ice Shelf and the sea ice in McMurdo sound, as well as across the Alpine Fault and a variety of farmer’s paddocks in New Zealand! She has worked on data from IceBridge 2009 since May, but this is her first experience of airborne fieldwork.
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